1. Field of the Invention
The present invention relates to a subject information obtaining apparatus, subject information obtaining method, and programs.
2. Description of the Related Art
In diagnosing breast cancer or the like, many biological information obtaining apparatuses using X-rays (mammography), acoustic waves and MRI (Magnetic Resonance Imaging) are used. Recently a biological information imaging apparatus, which propagates pulsed light in the biological tissue, detects acoustic waves (typically ultrasonic waves) generated by absorbing the propagating light on the surface of the biological tissue, and images the initial generation pressure distribution or light absorption coefficient distribution in the biological tissue, is receiving attention.
In order to obtain a light absorber in biological tissue, it is necessary to reconstruct an image using received signals on the acoustic waves. As an example of an image reconstruction method, a method for constructing an image by back projection of the signals (back projection method) is available. The back projection method is disclosed in Non-patent Literature 1 (NPL 1) “Photoacoustic imaging in biomedicine, REVIEW OF SCIENTIFIC INSTRUMENTS Vol. 77, 041101, (2006)”.
Another example of the image reconstruction method is estimating acoustic wave sources iteratively, and determining a least square solution with the signal to construct an image (iteration method). The iteration method is disclosed in Non-Patent Literature 2 (NPL 2) “Comparison of iterative reconstruction approaches for photoacoustic tomography, Proc. of SPIE Vol. 6437 64370 (2007)”.